Bazett's Formula Research Articles

QTc interval prolongation and risk of atrial fibrillation recurrence: a meta-analysis and observational cohort study.

Corrected QT interval (QTc) is a ventricular repolarization marker on electrocardiography. Previous studies evaluated its value in predicting atrial fibrillation (AF) occurrence. However, its predictive efficacy for AF recurrence remains controversial. We searched PubMed and Google databases for studies before January 2024 evaluating the association between QTc interval and AF incidence. A meta-analysis of the eligible datasets was conducted using Bazett's formula, with subgroup analysis to explore the heterogeneity. Additionally, thirty-eight patients with AF who underwent radiofrequency catheter ablation were enrolled and followed-up for 3-36 months. Univariate and multivariate Cox models were used to calculate the hazard ratios (HRs) and determine the relationship between clinical factors and AF recurrence. Kaplan-Meier survival analysis and ROC curve were conducted to assess the impact and predictive efficacy of individual factors. Eleven datasets from nine eligible studies were enrolled and meta-analysed. We found that patients with prolonged QTc interval was associated with a significantly higher AF incidence risk, and the risk increased with every 10-ms prolongation. However, this association was not significant in the AF recurrence subgroup. In our prospective cohort, the preoperative body mass index, QTc, left atrial diameter (LAD), and uric acid levels influenced AF recurrence. Multivariate Cox regression analysis identified LAD as an independent factor affecting AF recurrence in patients with a high predictive efficiency. Kaplan-Meier survival analysis showed that increased LAD (>4.5 cm) was associated with postoperative AF recurrence. Therefore, LAD has better predictive power and can be an indicator for predicting postoperative AF recurrence.

Association between QTc and Poincare plot in polycystic ovary syndrome in young adolescents: A cross-sectional study

ABSTRACT Context: PCOS is one of the most neglected noncommunicable diseases, and early detection would be of great value to primary care physicians. Sympathovagal imbalance detected using heart rate variability (HRV) can be used to detect early autonomic changes if any. Aim: The present study aimed to evaluate QTc and Poincare plot (nonlinear analysis of HRV) in young adolescent PCOS patients. Materials and Methods: It was a cross-sectional study involving 25 PCOS and 25 healthy individuals of age group 12–18 years. HRV was evaluated using the lead II ECG for 10 min from which QTc was calculated manually using the Bazett formula. Student’s t-test was used to assess differences between means. A P value < 0.05 was taken for statistical significance. The association between QTc and Poincare plot descriptors was assessed by Pearson’s correlation analysis. Results: HRV linear analysis domain represented as the LF/HF ratio was reported to significantly increased among the PCOS group (P = 0.04). Similarly, the nonlinear analysis of HRV by Poincare plot reported a significant decrease in SD1 (P = 0.04) and SD2 (P = 0.02). The heart rate was significantly increased among the PCOS group (P < 0.001). QTc did not show any significant increase among the PCOS group (P = 0.09). QTc was reported to be positively correlated with SD1 (r = 0.37, P < 0.01), SD2 (r-0.33, P = 0.02), LF HF ratio (r = 0.52, P < 0.001), and BMI (r = 0.92, P < 0.001), respectively. Conclusion: The study suggests that HRV nonlinear analysis can be used as a simple noninvasive tool to evaluate cardiovascular autonomic changes.

Optimal QT Correction Formula for Older Chinese: Guangzhou Biobank Cohort Study

Introduction: To identify the optimal QT correction formula for generating corrected QT (QTc) and cutoffs for prolonged QTc, and examine the associations with mortality and cardiovascular disease (CVD) in older Chinese. Methods: A prospective study included 24,611 Chinese aged 50+ years and without CVD at 2003–2008 from Guangzhou Biobank Cohort Study. QT interval was corrected by Bazett, Fridericia, Framingham and Hodges formulas. The slope and R2 of the QTc and heart rate regression were used to determine the optimal correction formula. The 95th percentile of QTc was used to defined prolonged QTc. Cox regression was used to examine associations of prolonged QTc with mortality and CVD. The net reclassification index was calculated to assess risk reclassification. Results: During an average follow-up of 15.3 years, 5,261 deaths and 5,539 CVD occurred. Optimal heart correction was observed for the Hodges formula, and Bazett formula performed the worst. Prolonged QTc corrected by Fridericia, Framingham and Hodges formulas had similar association strength with all-cause mortality, CVD mortality and incident CVD (especially coronary heart disease, myocardial infarction and ischemic stroke), with hazard ratios approximately being 1.25, 1.40, and 1.15, respectively. They also improved risk reclassification for all-cause mortality, CVD mortality and incident CVD by approximately 5%, 10%, and 6%, respectively. However, prolonged QTc corrected by Bazett formula was not associated with incident CVD and did not improve risk reclassification. Conclusions: Hodges formula outperformed other formulas for heart rate correction. Fridericia, Framingham, and Hodges formulas can be used for death and cardiovascular risk prediction.

Association between QT prolongation and cardiovascular mortality in cancer patients

BackgroundCancer patients’ vulnerability to QT prolongation contradicts certain anti-cancer drug usage. Until now, the QT prolongation’s impact on CV mortality in cancer patients remains unclear, potentially biasing therapeutic decisions.MethodsThis retrospective observational cohort included adult cancer patients with an electrocardiogram (ECG) performed in a tertiary hospital in Taiwan. The first performed ECGs after cancer diagnosis (n = 59,568) were analyzed. The corrected QT intervals by Bazett (QTcB), Fridericia (QTcFri), and Framingham (QTcFra) formulae were used to predict the 90-day and one-year CV mortality according to the Taiwan death registry.ResultsThe AUC of QTcB (90 days: 0.70, 1 year: 0.68) for predicting CV mortality was better than QTcFri and QTcFra (90 days: 0.63 and 0.50, 1 year: 0.65 and 0.56). Using the restricted cubic spline regression model adjusted by age and comorbidities, QTcB increased a significant but trivial risk of CV mortality at 90 days (hazard ratio, 1.007, P = 0.02) and one year (1.006, P < 0.01). Compared to those with QTcB < 500ms, the patients with QTcB ≥ 500ms were older and had more comorbidities and mortalities within one year. The incidence of sudden death and ventricular arrhythmias was only 0.2%. After adjusting for comorbidities, QTcB was neither associated with 90-day nor one-year CV mortality. In the patients already with QTcB ≥ 500ms, the patients receiving the unexpected uses of QT-prolonging drugs were not associated with higher one-year CV mortality than those without (P = 0.14).ConclusionsRather than a prolonged QT interval per se, comorbidities contributed to CV mortality and irreversible outcomes in cancer patients.

Correcting the Carotid Flow Time with the Formula of Bazett: mind the units.

Correcting the Carotid Flow Time with the Formula of Bazett: mind the units.

Uncovering possible silent acquired long QT syndrome using exercise stress testing in long-term pediatric acute lymphoblastic leukemia survivors.

An example of chemotherapy-induced cardiotoxicity in cancer survivors is acquired long QT syndrome (aLQTS), which may cause serious yet preventable life-threatening consequences. Our objective was to identify and characterize childhood acute lymphoblastic leukemia (ALL) survivors with possible aLQTS using maximal exercise testing. In this cross-sectional study with exploratory analysis, a total of 250 childhood ALL survivors were evaluated for abnormal QT interval prolongation using the McMaster cycle exercise test. A total of 198 survivors (102 males; 96 females), having reached their peak (mean 32.1 ± 8.4 mL/kg/min; range 15.5-57.8 mL/kg/min), were included in our analyses. Two survivors were excluded for possible congenital LQTS. QT intervals were corrected for heart rate using the Bazett, Fridericia, and Rautaharju formulas at rest (supine, sitting, and standing positions), at the end of each stage of the CPET, and at 1, 3, and 5 minutes into the recovery period. The corrected QT (QTc) of borderline (n = 37) and long QT survivors (n = 20) was significantly longer than normal survivors (n = 141) at rest, exercise, and recovery. Out of 57 survivors presenting an abnormal QTc prolongation, 40 survivors (70%) showed no QT interval anomalies at rest but developed various anomalies during exercise. No significant differences were found between the groups for any of the measured clinical characteristics or cardiac parameters. The standardization of exercise testing in the regular follow-up of oncology patients is necessary for appropriate cardiac prevention and surveillance to enhance the health and quality of life of the ever-increasing number of cancer survivors.

Validation of a Demography-Based Adaptive QTc Formula using Pediatric and Adult Datasets Acquired from Humans and Guinea Pigs.

A variety of QT rate-correction (QTc) formulae have been utilized for both clinical and research purposes. However, these formulae are not universally effective, likely due to significant influences of demographic diversity on the QT-HR relationship. To address this limitation, we proposed an adaptive QTc (QTcAd) formula that adjusts to subject demographics (i.e., age). Further, we compared the efficacy and accuracy of the QTcAd formula to other widely used alternatives. Using age as a demographic parameter, we tested the QTcAd formula across diverse age groups with different heart rates (HR) in both humans and guinea pigs. Utilizing retrospective human (n=1360) and guinea pig electrocardiogram (ECG) data from in-vivo (n=55) and ex-vivo (n=66) settings, we evaluated the formula's effectiveness. Linear regression fit parameters of HR-QTc (slope and R²) were utilized for performance assessment. To evaluate the accuracy of the predicted QTc, we acquired epicardial electrical and optical voltage data from Langendorff-perfused guinea pig hearts. In both human subjects and guinea pigs, the QTcAd formula consistently outperformed other formulae across all age groups. For instance, in a 20-year-old human group (n=300), the QTcAd formula successfully nullified the inverse HR-QT relationship (R²=5.1E-09, slope=-3.5E-05), while the Bazett formula (QTcB) failed to achieve comparable effectiveness (R²= 0.20, slope=0.91). Moreover, the QTcAd formula exhibited better accuracy than the age-specific Benatar formula (QTcBe), which overcorrected QTc (1-week human QT: 263.8±14.8 ms, QTcAd: 263.8±7.3 ms, p=0.62; QTcBe: 422.5±7.3 ms, p<0.0001). The optically measured pseudo-QT interval (143±22.5 ms, n=44) was better approximated by QTcAd (180.6±17.0 ms) compared to all other formulae. Furthermore, we demonstrated that the QTcAd formula was not inferior to individual-specific QTc formulae. The demography-based QTcAd formula showed superior performance across human and guinea pig age groups, which may enhance the efficacy of QTc for cardiovascular disease diagnosis, risk stratification, and drug safety testing. Corrected QT (QTc) is a well-known ECG biomarker for cardiovascular disease risk stratification and drug safety testing. Various QT rate-correction formulae have been developed, but these formulae do not perform consistently across diverse datasets (e.g., sex, age, disease, species). We introduce a novel QTc formula (QTcAd) that adapts to demographic variability, as the parameters can be modified based on the characteristics of the study population. The formula (QTcAd = QT + (|m|*(HR-HR mean )) - includes the absolute slope (m) of the linear regression of QT and heart rate (HR) and the mean HR of the population (HR mean ) as population characteristics parametersˍUsing datasets from both pediatric and adult human subjects and an animal model, we demonstrate that the QTcAd formula is more effective at eliminating the QT-HR inverse relationship, as compared to other commonly used correction formulae.

Evaluation of the Relationship Between Microalbuminuria/Creatinine Ratio and QTc Dispersion in Type 2 Diabetes Mellitus

Objective: The assessment of QTc dispersion (QTd) is of importance in determining the risk of ventricular arrhythmias and cardiac autonomic neuropathy (CAN) in patients with diabetic nephropathy (DN). Our study explored the relationship between the microalbumin/creatinine (MA/crea) ratio and QT(cd) in the context of CAN development in DN. Material and Methods: We selected fifty individuals with a spot urine MA/crea ratio of less than 30 as the control group and fifty individuals with an MA/crea ratio between 30 and 300 as the patient group. QT intervals were calculated using the Bazett formula, taking into account the heart rate. Results: In contrast to the control group, the patient group exhibited a considerably higher median QTc min value (380.63 msn, 361.44–397.30, p: 0.042) and a statistically significant increase in the median QTc max value (439.98 msn, 420.17–460.22, p=0.005). Furthermore, the median MA/crea value (82, 60–300, p&lt;0.0001) was found to be highly significant. However, the median QT(cd) value (61.25 msn, 49.91–81.70, p=0.066) was only marginally significant, with no statistically significant difference between the two groups. It is worth noting that both groups showed a significant difference in terms of QTd (p&lt;0.001). In the control group, where DN had not yet developed, the QT(cd) value could be detected before an increase in the MA/crea value. Conclusion: The findings that both the control group and the patient group exhibited elevated QTcd values suggest that this parameter may be a viable predictor of cardiovascular risk. Furthermore, it is conceivable that QTcd could serve as an early warning sign for cardiovascular risk in diabetic patients who have not yet reached the stage of microalbuminuria.

Determinants/Predictors of QT Abnormalities in Patients on Psychotropic Medications in a Nigerian Tertiary Hospital.

Cardiovascular disease is a major global burden and a leading cause of premature death among patients with severe mental illness. Over time, research and clinical practice have paid increased attention to the impact of psychiatric medications on cardiac repolarization. In a resource-limited setting, it is common for psychotropic medications to be initiated and maintained in an outpatient setting without baseline or follow up ECG. This study evaluated the determinants and predictors of QT abnormalities among patient taking psychotropic drugs. We conducted a cross-sectional study in a population of 150 psychiatric patients on psychotropics and 75 controls. We studied the effects of various psychotropic drugs on QT dispersion (QTd) and corrected QT interval (QTc) as well as correlation with the types and dosages of psychotropic drugs used. All the subjects had detailed clinical examination and resting electrocardiogram (ECG) at 25mm/sec done. QTc was determined using Bazett formula and QTd was determined by subtracting shortest from longest QT in 12-lead ECG. The prevalence of prolonged QTc and QTd as well as the mean QTc and QTd were significantly higher in patients than the control group. The mean QTc was significantly higher in patient on typical antipsychotics compared to those on atypical antipsychotics. Age, heart rate and antipsychotic dose in chlorpromazine equivalent were predictors of QTc with the heart rate being the most powerful predictor among them. Psychotropic drugs use is associated with QTc and QTd prolongation with age, heart rate and antipsychotic dose as predictors of QTc.

Handgrip strength test for the diagnosis of long QT syndrome

Long QT syndrome (LQTS) assessment is based on the QT/ÖRR equation (the so-called Bazett's formula) and calculating the corrected QT (QTc). However, this formula reliably estimates the QT interval in the heart rate range (HR) of 60-90 bpm, which makes it difficult to diagnose LQTS in patients with sinus bradycardia, typical of this disease.Aim. To improve the LQTS diagnosis in patients with sinus bradycardia using the handgrip strength test.Material and methods. A total of 188 patients aged 5-53 years (16 [13;17]) were examined: group I — 40 healthy children aged 9-17 years (14 [12;16]); group II — 98 athletes with sinus bradycardia &lt;60 bpm aged 16 [16;17] years; group III — 50 patients with LQTS aged 5-53 years (12 [10;16]). The handgrip strength test consisted of regular rhythmic compression of a hand expander with a resistance of 20 kg until the heart rate increased &gt;60 bpm. The patients had an electrocardiogram recorded twice before and after the handgrip test. Heart rate, QT and QTc intervals were analyzed.Results. In all groups, after using the expander, there was a significant increase in heart rate, QT interval shortening and QTc interval prolongation. QTc interval prolongation after the handgrip test &gt;460 ms was a highly sensitive marker of LQTS (Se 96%, Sp 60%).Conclusion. Proposed handgrip test for sinus bradycardia makes it possible to increase heart rate, which ensures a more correct use of the Bazett's formula for assessing the corrected QT interval (QTc). QTc interval prolongation over 460 ms after the handgrip test is a highly sensitive additional marker for identifying patients with LQTS.

Electrocardiographic manifestations in female team handball players: analyzing ECG changes in athletes.

Long-term intense training leads to structural, functional, and electrical remodeling of the heart. How different sports affect the heart has not been fully investigated, particularly for female athletes. The aim of the present study was to investigate the morphology of 12-lead resting electrocardiogram (ECG) in elite female handball players compared to non-athlete female subjects. Potential changes will be explored to see if they could be explained by differences in cardiac dimensions and exercise hours. A cross-sectional study of 33 elite female team handball players compared to 33 sex and age-matched, non-athletic controls (age range 18-26 years) was performed. All participants underwent a resting 12-lead ECG and an echocardiographic examination. ECG variables for left ventricular hypertrophy and durations were evaluated and adjusted for cardiac dimensions and exercise hours using ANCOVA analysis. A linear regression analysis was used to describe relation between echocardiographic and ECG measures and exercise hours. The female handball players had larger cardiac dimensions and significantly lower heart rate and QTc duration (Bazett's formula) as well as increased QRS and QT durations compared to controls. The 12-lead sum of voltage and the 12-lead sum of voltage ∗ QRS were significantly higher among handball players. Changes in ECG variables reflecting the left ventricle could in part be explained by left ventricular size and exercise hours. Correlation with exercise hours were moderately strong in most of the echocardiographic measures reflecting left ventricular (LV), left ventricular mass (LVM), left atrium (LA) and right atrium (RA) size. Poor to fair correlations were seen in the majority of ECG measures. Female team handball players had altered ECGs, longer QRS and QT durations, higher 12-lead sum of voltage and 12-lead sum of voltage ∗ QRS as well as shorter QTc (Bazett's formula) duration compared to non-athletic controls. These findings could only partly be explained by differences in left ventricular size. Despite larger atrial size in the athletes, no differences in P-wave amplitude and duration were found on ECG. This suggest that both structural, and to some degree electrical remodeling, occur in the female team handball players' heart and highlight that a normal ECG does not rule out structural adaptations. The present study adds knowledge to the field of sports cardiology regarding how the heart in female team handball players adapts to this type of sport.

Adolescents on psychotropic treatment displayed longer corrected QT intervals than unmedicated controls when they rose rapidly from the supine position.

Psychotropic medication can contribute to arrhythmia and identifying individuals at risk is crucial. This Swedish study compared the corrected QT (QTc) intervals of adolescents on psychotropic medication with unmedicated controls, when supine and after rising rapidly. The study was carried out at Östersund County Hospital in March 2022 and February to March 2023. It comprised 16 cases, aged 10-17 years and 28 controls. QTc intervals were measured with electrocardiography and calculated using Bazett's and Fridericia's formulas. Univariate and multiple linear regressions were used to assess differences in QTc intervals between the cases and controls and across sex, age and body mass index. The mean QTc interval when supine, calculated with Bazett's formula, was longer for the adolescents on psychotropic medication than the controls (p = 0.046). The same was true for the mean QTc interval after rising rapidly from the supine position, calculated with both Bazett's formula (p = 0.009) and Fridericia's formula (p = 0.007). Mean QTc intervals varied by sex and age groups. Psychotropic medication prolonged QTc intervals, particularly in girls. Longer QTc intervals were found in adolescents on psychotropic medication, particularly after rising rapidly from the supine position.

Endocardial repolarization dispersion in BrS: A novel automatic algorithm for mapping activation recovery interval.

Repolarization dispersion in the right ventricular outflow tract (RVOT) contributes to the type-1 electrocardiographic (ECG) phenotype of Brugada syndrome (BrS), while data on the significance and feasibility of mapping repolarization dispersion in BrS patients are scarce. Moreover, the role of endocardial repolarization dispersion in BrS is poorly investigated. We aimed to assess endocardial repolarization patterns through an automated calculation of activation recovery interval (ARI) estimated on unipolar electrograms (UEGs) in spontaneous type-1 BrS patients and controls; we also investigated the relation between ARI and right ventricle activation time (RVAT), and T-wave peak-to-end interval (Tpe) in BrS patients. Patients underwent endocardial high-density electroanatomical mapping (HDEAM); BrS showing an overt type-1 ECG were defined asOType1, while those without (latent type-1 ECGandLType1) received ajmaline infusion. BrS patients only underwent programmed ventricular stimulation (PVS). Data were elaborated to obtain ARI corrected with the Bazett formula (ARIc), while RVAT was derived from activation maps. 39 BrS subjects (24 OType1 and 15 LTtype1) and 4 controls were enrolled. OType1 and post-ajmaline LType1 showed longer mean ARIc than controls (306 ± 27.3 ms and 333.3 ± 16.3 ms vs. 281.7 ± 10.3 ms, p = .05 and p < .001, respectively). Ajmaline induced a significant prolongation of ARIc compared to pre-ajmaline LTtype1 (333.3 ± 16.3 vs. 303.4 ± 20.7 ms, p < .001) and OType1 (306 ± 27.3 ms, p < .001). In patients with type-1 ECG (OTtype1 and post-ajmaline LType1) ARIc correlated with RVAT (r = .34, p = .04) and Tpec (r = .60, p < .001), especially in OType1 subjects (r = .55, p = .008 and r = .65 p < .001, respectively). ARIc mapping demonstrates increased endocardial repolarization dispersion in RVOT in BrS. Endocardial ARIc positively correlates with RVAT and Tpec, especially in OType1.

QTc intervals at rest and during exercise assessed by group correction formulas in survivors of childhood acute lymphoblastic leukemia

IntroductionEarly signs of subclinical cardiac damage must be identified before they turn into clinical manifestations. Tailoring a formula is relevant for precise QTc evaluation in childhood acute lymphoblastic leukemia (ALL) survivors considering they are at risk of long-term cardiac problems. Therefore, we aim to develop group heart rate correction formulas for QT intervals in childhood ALL survivors at rest and during exercise, and to assess the applicability of these methods across a variety of risk groups exposed to diverse chemotherapy dosages. MethodsTwo hundred and fifty childhood ALL survivors in the PETALE study were classified into 3 groups depending on their prognostic risk group. ECG measurements (QT and RR intervals) were made at rest and during a cardiopulmonary exercise test. QT correction for heart rate was applied using 5 different formulas, which included 2 previously published formulas and 3 group-specific formulas for each sex. ResultsThe QT/RR relation showed 2 different curves between rest and during exercise, which was worse for females. Group-specific QTc formulas allowed adequate heart rate-corrected QT interval, independently of the cumulative dose of doxorubicin received during treatment. Group-specific formulas showed significantly shorter QTc intervals than QTc from Bazett's formula. QTc (Bazett's formula) values surpassed the established clinical norm in 22 males (11%) and 22 females (11%), with a majority occurring during exercise, affecting 15 males (7.5%) and 10 females (5%). ConclusionThis study shows the applicability of personalized group correction of QT/RR data in childhood ALL survivors. Our comprehensive assessments (spanning rest, exercise, and recovery) is an effective approach for risk stratification of cardiac complications in childhood ALL survivors.

Incidence of QT interval prolongation during arsenic trioxide-based therapy in a sample of Iraqi adult patients with acute promyelocytic leukemia (a single-center experience)

Abstract: BACKGROUND: Arsenic trioxide (ATO) regimen is now the standard of care for acute promyelocytic leukemia (APL). The complete remission and possible cure are reported to be 50%–80% of APL patients. Prolongation of the QT interval has been consistently observed in clinical trials with ATO, which is known to have a direct effect on cardiac repolarization with the recommendations for management include electrocardiogram (ECG) monitoring, discontinuation of drugs that prolong the QT interval, and careful repletion of serum potassium and magnesium. OBJECTIVES: To study the incidence and clinical consequences of QT prolongation in a sample of Iraqi APL patients treated with ATO. PATIENTS AND METHODS: A prospective, cross-sectional study was conducted on 24 adult patients with newly diagnosed APL at Baghdad Teaching Hospital. ECG was performed at baseline and twice weekly till the end of induction treatment course. Corrected QT interval was calculated based on Bazett and Fridericia formulas (QTc interval of more than 500 ms is considered dangerous): Serum potassium, calcium, and magnesium levels were also measured simultaneously. RESULTS: The mean QT at baseline was 424 ± 18 ms and 402 ± 15 ms by Bazett and Fridericia, respectively, and at the end of induction, the mean QT was 436 ± 20 ms and 418 ± 20 ms by Bazett and Fridericia, respectively. The rate of developing prolonged QT was 62.5% by Bazet, in which 15 patients developed prolonged QT (at any time point). The comparison between prolonged and dangerous QT groups by Bazet showed significant difference, in which QT-related complications were associated with dangerous QT (&gt;500 ms) prolongation significantly, while Fridrica method did not label these patients as having dangerous QT prolongation. The change in QT started as early as 1 week after treatment, the comparison between baseline QT and QT at week 1 showed that there was significant increase in QT. The electrolytes analysis and comparison with baseline results for potassium, magnesium, and calcium showed that there were no significant differences over time for tested electrolytes. CONCLUSION: Bazett formula is useful to monitor Iraqi patients with APL who are treated with ATO for the detection of dangerous prolongation of QT.

QT interval in children with orthostatic dysregulation: Changes in standing load.

The corrected QT interval (QTc) is affected by changes in autonomic sympathovagal modulation. The aim of this study was to determine whether children with orthostatic dysregulation (OD) have a longer QTc while standing than children without OD. We retrospectively assessed patients who underwent the Schellong test and electrocardiography between November 2016 and November 2019. Patients who met the criteria of OD subtypes according to the Japanese clinical guidelines for juvenile OD (version 1) were classified as OD positive (the OD-positive group), and patients who did not meet the criteria were classified as OD negative (the OD-negative group). There were 73 patients in the OD-positive group and 52 patients in the OD-negative group. Baseline heart rate, QT interval, and QTc were comparable between the OD-positive and OD-negative groups. Heart rate after standing was significantly higher in the OD-positive group than in the OD-negative group (median: 33 bpm vs. 21 bpm, p < 0.001). Further, shortening of QT interval after standing was greater in the OD-positive group than in the OD-negative group (median: 19 ms vs. 8 ms, p = 0.015). The QTc significantly increased from baseline to standing in both groups. Changes in the QT interval corrected by Bazett's formula were greater in the OD-positive group than in the OD-negative group (median: 73 ms vs. 42 ms, p < 0.001). The QTc increased significantly from baseline to standing in the OD-positive group. Thus, a high QTc while standing could be considered an auxiliary marker for OD diagnosis.

Noninvasive Assessment of Cardiopulmonary Hemodynamics Using Cardiovascular Magnetic Resonance Pulmonary Transit Time.

Introduction: Pulmonary transit time (PTT) is the time it takes blood to pass from the right ventricle to the left ventricle via the pulmonary circulation, making it a potentially useful marker for heart failure. We assessed the association of PTT with diastolic dysfunction (DD) and mitral valve regurgitation (MVR). Methods: We evaluated routine stress perfusion cardiovascular magnetic resonance (CMR) scans in 83 patients including assessment of PTT with simultaneously available echocardiographic assessment. Relevant DD and MVR were defined as exceeding Grade I (impaired relaxation and mild regurgitation). PTT was determined from CMR rest perfusion scans. Normalized PTT (nPTT), adjusted for heart rate, was calculated using Bazett's formula. Results: Higher PTT and nPTT values were associated with higher grade DD and MVR. The diagnostic accuracy for the prediction of DD as quantified by the area under the ROC curve (AUC) was 0.73 (CI 0.61-0.85; p = 0.001) for PTT and 0.81 (CI 0.71-0.89; p < 0.001) for nPTT. For MVR, the diagnostic performance amounted to an AUC of 0.80 (CI 0.68-0.92; p < 0.001) for PTT and 0.78 (CI 0.65-0.90; p < 0.001) for nPTT. PTT values < 8 s rule out the presence of DD and MVR with a probability of 70% (negative predictive value 78%). Conclusion: CMR-derived PTT is a readily obtainable hemodynamic parameter. It is elevated in patients with DD and moderate to severe MVR. Low PTT values make the presence of DD and MVR-as assessed by echocardiography-unlikely.

QT prolongation predicts all-cause mortality above and beyond a validated risk score

IntroductionQT prolongation is a risk factor for life-threatening arrhythmias and sudden cardiac death. In large cohorts, QT interval was associated with all-cause mortality, but these analyses may contain residual confounding. Whether the QT interval provides prognostic information above and beyond a validated mortality risk score is unknown. We hypothesized that QT interval on ECG will independently predict mortality after adjustment for the Care Assessment Needs (CAN) score, which was validated to predict mortality nationwide at the Veterans Administration (VA) (c-index 0.86). MethodsOutpatients with an ECG at the Minneapolis VA from 2012 to 2016 were included in this retrospective cohort study. ECGs with ventricular rate < 50 or > 100 beats/min and those with QRS > 120 ms were excluded. QT intervals were corrected (QTc) using the Bazett's formula. CAN score, calculated within 1-week of the ECG, was obtained from the VA Corporate Data Warehouse. ResultsOf the 31,201 patients, 427 (1.4%) had QTc ≥ 500 ms, 1799 (5.8%) had QTc 470–500 ms and 28,975 (92.9%) had QTc < 470 ms. Compared to those with QTc < 470 ms, CAN-adjusted odds ratios (OR) for 1-year mortality (1.76 for QTc 470–500 and 2.70 for QTc > 500 ms; p < 0.0001 for both) and for 5-year mortality (1.75 for QTc 470–500 and 2.48 for QTc > 500 ms; p < 0.0001 for both) were significantly higher in those with longer QTc. C-index for CAN score and QTc predicting 1-year mortality was 0.837. ConclusionsQT prolongation predicts all-cause mortality independently of a validated mortality risk prediction score.

Assessment of repolarization dispersion by using endocardial unipolar electrograms in patients with brugada syndrome and spontaneous coved-type electrocardiographic pattern

Abstract Background Coved-type electrocardiographic (ECG) pattern of patients with Brugada syndrome (BrS) is secondary to action potential lengthening in the right ventricular outflow tract (RVOT) epicardium. This may be approximated by activation-recovery interval (ARI), a marker of local repolarization dispersion. Purpose Our aim was to examine epicardial repolarization dispersion by ARI in the RVOT in patients with BrS and its correlation with conduction slowing and Tpeak-Tend (Tpe) interval, a marker of altered repolarization on surface ECG previously associated with a higher arrhythmic risk in this setting. Methods 24 patients with coved-type BrS phenotype underwent an invasive electrophysiological evaluation with endocardial high-density 3D mapping and programmed ventricular stimulation (PVS). Mapping data was exported and converted into MatLab format using OpenEP. Paraview was used to select a region of interest (ROI) specifically comprising of sub-pulmonary RVOT and RV free wall. ARI was calculated for each point of the ROI using a semi-automated algorithm with the Wyatt method and corrected with the Bazett formula (ARIc). The values were then interpolated to create ARI maps. For each patient, we calculated the value of ARIc at 75% of the distribution (ARIcQ3) and mean ARI for the values in the interval above ARIcQ3 (meanARIcQ3); ARIcQ3 points were also used to create maps. Activation maps were used to determine right ventricular activation time (RVAT). Tpe intervals were calculated with the tangent method on V1, V2 and V3 of 20 low-noise sinus beats recorded during the procedure, and then corrected with the Bazzett formula. Results Out of 24 patients, 6 had inducible VT/ VF during PVS (PVS+) while 18 did not (PVS-). Average ARI, ARIc, ARIcQ3, and meanARIcQ3 were 291.4 ± 22.1 ms; 306.0 ± 27.3 ms; 335.1 ± 28.3 ms; 353.1 ± 30.3 ms, respectively. Average Tpe was 75.0 ± 7.3 ms, with a mean corrected Tpe of 79.0 ± 10 ms. Mean RVAT was 111.9 ± 30.7 ms. Zones with ARIcQ3 were all located into the anterior and subpulmonary RVOT. We found a correlation between ARIcQ3 and mean corrected Tpe (R=0.58, p=0.003), and between meanARIcQ3 and mean corrected Tpe (R=0.65, p&amp;lt;0.001). A good correlation was also found between ARIcQ3 and RVAT (R=0.5441, p=0.009), and meanARIcQ3 and RVAT (R=0.49, p=0.02). No significant differences were found between PVS+ and PVS- patients. Conclusions Our results show the presence of zones with long ARI within RVOT of BrS with type-1 phenotype, indicating marked local repolarization dispersion. Longer ARIs correlate with altered repolarization on surface ECG and with prolongation of local activation time. ARI mapping can help identify repolarization dispersion and should be evaluated in the setting of a multi-parametric risk assessment in BrS with spontaneous coved-type ECG.

Relationship between corrected QT prolongation and new-onset atrial fibrillation in the general Japanese population

Abstract Background The QT interval, an electrocardiogram (ECG) parameter, can be corrected for heart rate, giving the QTc. The QTc is an indicator of ventricular repolarisation and is widely used as a predictor of ventricular arrhythmia. Recent studies have reported a relationship between prolonged QTc and atrial fibrillation (AF) development. Purpose We investigated whether a relationship between QTc prolongation and new-onset AF could be identified in the general Japanese population. Methods This retrospective study evaluated the annual health check-up data of 103,304 adults (50,438 males; age, 54±15 years) that did not have AF at baseline, from April 2005 to October 2018. Most participants underwent annual health examinations as recommended by the Japanese health welfare policy. The QTc times were calculated with the Bazett formula (QTc=QT/√RR), using the mean QT and RR intervals. Participants were grouped according to QTc time: long-QTc group (males, &amp;gt;440 ms; females, &amp;gt;460 ms) and normal-QTc group. AF was diagnosed using a 12-lead surface ECG. Logistic regression analyses were performed to determine the strength of the association between prolonged QTc and new-onset AF. Multivariate analyses were adjusted for clinical variables (age, sex, obesity, hypertension, dyslipidaemia, diabetes, estimated glomerular filtration rate, and habitual drinking). Results The median follow-up time for the total study population was 6 years. During follow-up, 341 (0.3%) new cases of AF were recorded. Univariate analysis revealed a significant increase in new-onset AF in the long-QTc group (odds ratio [OR], 2.80; 95% confidence interval [CI], 1.85–4.25; p&amp;lt;0.001). After adjusting for clinical variables, multivariate analysis revealed that a long QTc was significantly associated with new-onset AF (OR, 1.71; 95% CI, 1.12–2.61; p=0.013). In the multivariate analysis, age (OR, 1.06; 95% CI, 1.05–1.07; p&amp;lt;0.001), sex (OR, 2.55; 95% CI, 1.95–3.33; p&amp;lt;0.001), obesity (OR, 1.46; 95% CI, 1.16–1.84; p=0.001), and habitual drinking (OR, 1.90; 95% CI, 1.50–2.41; p&amp;lt;0.001) were also significant predictors of new-onset AF. Conclusions Prolonged QTc is associated with an increased risk of new-onset AF in the general Japanese population. The mechanism of this causal relationship requires further investigation.